M42 Engine Harness Connections

[gusgriff]

Swapping M42 engines. Need some guidance on a couple engine harness cable connections. The donor car engine had the cables hanging loose and the 1995 318Ti car I bought to rebuild had them disconnected as well with loose components. The person who discovered the head was cracked did not reassemble everything.

Is there a picture or diagram that shows the connection locations? I am very sure I have all the components because I have two of components?

Coming out of the junction box under the Intake Manifold are two cables with rectangular spring connectors that I cannot identify what they connect to. I know the cables connect either to the Vaccum Reservior or Box and maybe the Throttle Valve Switch. One cable is about a 18 inches longer and suspect it connects to the Throttle Valve Switch.

I am considering purchasing new sensor components because I do not know how fragile they are and the plastic/rubber is brittle. The Knock/Ping Sensors plastic outer covers were cracked. All belts, hoses and the plastic cooling pipe will be replaced for PM.

[bmwman91]

The throttle potentiometer is a 3-pin plug & the only one coming out of that part of the junction box. The 2-pin ones are for the oil pressure switch, coolant temp sensor (ECU), coolant temp sensor (temp gauge) & evaporative purge valve. The evap valve wire splits off of the AFM loom, and the temp sensor for the ECU is the one further back on the head (and I think that its plug is on its own wire). The confusing part is figuring out which plugs are for the oil pressure switch & coolant gauge sender. Hook them up one way, run the car until it warms up and if you get weird behavior (oi light slowly lights up and temp needle shoots to the red all at once) switch them.

[wazzu70]

Any way to take a picture of the connectors in question?

The box under the intake has lots of connections. Off the top of my head: oil pressure, ecu temp, gauge temp, throttle position, Air flow meter, EVAP valve?

I think thats all. I would take a picture, but my harness is heavily thinned

[gusgriff]

Thanks Guys.  I have taken more than 25 pictures of the donor engine cable harness and connections and labeled all know.  All were connect to a sensor/switch except 3 or 4. Using what was still connected to the recipient car I have been able to determine 1 or 2 more.  This leaves the two mentioned in the original post with a 3rd that I am 75% sure is correct.

I can PM you pictures or Photobucket or similar service.

Added after original Reply

I did already have the 3 plug throttle potentiometer labeled properly.  The cables in question are 2 plug and exit the bottom of the junction box with 4 other cables with ring connector and 2 of these connect to the alternator.  The other two ring connectors may be to the starter or a ground.  I have the Idle Regulating Valve, 2 knock sensors, 2 head temp sensor/switches, oil pressure sensor, Trigger Contact and Pulse Generator cables labeled.  These were labeled before I disconnected them from the donor engine.  I am 75% sure I have the Vacuum Switch/Box cable labeled correct.   I now believe the shorter of the two cables connects to the Vacuum Reservoir.  I think the Vacuum Reservoir is black plastic 2-3 inched in diameter and is 2-3 inched long and mounts in a rubber ring.  There something called the Electric Valve near the Vacuum Reservoir.  I am confused is there a large black plastic tank ( 4-5 inches diameter and 6-8 inches long) looking part maybe called the Vacuum Tank that mounts to the inner fender?  If I am correct, this leaves the long cable.

[bmwman91]

Aah yeah, there are 3 ring terminal wires that go to the starter. They should all be of different sizes so you can't mix them up. I totally forgot about this...this should have everything you need.

http://www.m42club.com/forums/showthread.php?t=5098

[gusgriff]

I still do not know where the long cable with the 2 two prong connector connects.  I did determine that the Electric Valve in attached to the bracket with the Vacuum Reservoir. I am sure the shorter cable with the two prong connector must connect to this Electric Valve/Vacuum Reservoir assembly.

Added

The cable coming from the bottom of the junction box has 6 connections.  Four are terminated with ring connectors and the other two terminate with two prong connectors and are the long and short cables mentioned above.

Mentioned above are 3 ring terminal wires that go to the starter.  I gave the wrong info about the ring connector cables  I said 4 and 2 attach to the alternator. It is actually 3 cables from the junction box withprogressively smaller ring connectors.   Two terminate with ring connectors but the 3rd cable splices into a larger cable that has a large ring connector on one end and  two smaller ring connectors with a rubber flap/cover that attach to the alternator.  I assume the large ring connector and the two progressively smaller ring connectors on the other two cables connect to starter.  Sorry able the confusing explanation.